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Peracetic acid (PAA) is an effective oxidant capable of solubilising lignin and efficiently depolymerising it to selective phenolic compounds; however, the specific role by which PAA initiates the depolymerisation is still elusive. Herein, interaction between PAA and the lignin macromolecule and the consequent structural changes of the latter were studied by characterising the lignin packing structure and its associated changes during the oxidation process. While the lignin packing structure and its changes associated with the PAA-mediated oxidation were probed by X-ray diffraction, the impact of the PAA on different chemical functionalities present in the lignin structure was established by 13C and 1H–13C heteronuclear single-quantum coherence nuclear magnetic resonance (NMR) spectroscopy. Combining the NMR spectroscopy results, and the product distribution, we conclude that the predominant reaction pathway for the oxidative depolymerisation of lignin with PAA is the Baeyer–Villiger oxidation of the ketone formed by the oxidation of the benzylic hydroxyl group adjacent to the β-O-4 linkage. The experimental evidence provided herein corroborated that PAA instigates oxygen insertion to the lignin macromolecule resulting in disruption of its packing structures and facilitates depolymerisation. We also investigated various metal oxide and mixed metal oxide catalysts to identify effective catalysts that further enhance the efficiency of PAA-mediated depolymerisation of lignin and produce selective monomeric phenolic compounds. Techno-economic analysis was also conducted to identify the key parameters associated with this oxidative process that need to be considered for possible commercial application.

The recent emergence of a robust renewable ethanol industry has provided a sustainable platform molecule toward the production of value-added chemicals and fuels; what is lacking now are viable conversion processes from ethanol that can displace the current production pathways from non-renewable pathways. Here in the work, we demonstrate the highly selective conversion of ethanol to higher alcohols over low copper loaded MgAl mixed oxide catalysts, with 50% improvement in higher alcohol yields over the current state of the art. At these copper concentrations, atomically dispersed Cu1+ were found to be stable even at highly reductive conditions and highly active towards higher alcohol products (e.g. butanol, hexanol) while suppressing side reaction pathways and leading to extended lifetimes of over 150 hours time on stream. Technoeconomic analysis conducted based on these experimental results demonstrate that this catalytic system is cost-competitive with the conventional process. This marks significant progress in the development of Guerbet coupling of ethanol as a viable renewable process and offers a pathway toward sustainable chemical and fuel production.

Light olefins (C2–C5) are high-value platform chemicals used to produce plastics, lubricants, coating material, and surfactants, and can be intermediates to produce transportation fuels. In this study we report on the development of a Co-based catalyst for direct conversion of fossil as well as biomass derived syngas into light olefins that enables high conversion and olefin/paraffin (O/P) product ratio, minimal selectivity to CO2 (

The number of publications in electrochemical energy storage has increased exponentially in the past decades, focusing mostly on materials science. The electrochemical process controlling the observed overall performances is often not well discussed. This article highlights the importance of understanding rate-limiting steps in the electrochemical process which change dynamically at different conditions and scales. Applying electrochemistry to identify and overcome those rate-limiting steps in the electrochemical devices is the prerequisite to discovering effective solutions and designing different batteries to further advance electrochemical energy storage systems for a broad range of various applications.

A new process for direct conversion of either levulinic acid (LA) or γ-valerolactone (GVL) to hydrocarbon fuel precursors was studied. The process involves passing an aqueous solution of LA or GVL containing a reducing agent, such as ethylene glycol or formic acid, over a ketonization catalyst at 380–400 °C and atmospheric pressure to form a biphasic liquid product. The organic phase is significantly oligomerized and deoxygenated and comprises a complex mixture of open-chain alkanes and olefins, aromatics, and low concentrations of ketones, alcohols, ethers, and carboxylates or lactones. Carbon content in the aqueous phase decreases with decreasing feed rate; the aqueous phase can be reprocessed through the same catalyst to form additional organic oils to improve carbon yield. Catalysts are readily regenerated to restore initial activity. The process might be valuable in converting cellulosics to biorenewable gasoline, jet, and diesel fuels as a means to decrease petroleum use and decrease greenhouse gas emissions.

A highly versatile ethanol conversion process to selectively generate high value compounds is presented here. By changing the reaction temperature, ethanol can be selectively converted to >C2 alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3 catalyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensation or the acetone formation is the path taken in changing the product composition. This article contains the catalytic activity comparison between the mono-functional and physical mixture counterpart to the hydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

In the base catalyzed ethanol condensation reactions, the calcined MgO–Al2O3 derived hydrotalcites used broadly as catalytic material and the calcination temperature plays a big role in determining the catalytic activity. The characteristics of the hydrotalcite material treated between catalytically relevant temperatures 450 and 800 °C have been studied with respect to the physical, chemical, and structural properties and compared with catalytic activity testing. With the increasing calcination temperature, the total measured catalytic basicity dropped linearly with the calcination temperature and the total measured acidity stayed the same for all the calcination temperatures except 800 °C. However, the catalyst activity testing does not show any direct correlation between the measured catalytic basicity and the catalyst activity to the ethanol condensation reaction to form 1-butanol. The highest ethanol conversion of 44 % with 1-butanol selectivity of 50 % was achieved for the 600 °C calcined hydrotalcite material.

The syngas hydrogenation activity of the Co–Ni bimetallic catalyst containing total metal loading less than 10 wt% was prepared via a wet impregnation method and was studied with respect to the reaction temperature and the catalyst composition. Among the hydrocarbons generated, small olefinic compounds between C2 and C7 (up to 40%) were the highest in the product mixture. The olefin to paraffin ratio for C3 hydrocarbon is around 8. For all variables tested, the product distribution contains up to 10% oxygenates along with the hydrocarbon compounds. An acidic alumina containing reactor was added followed by the Co–Ni containing reactor to demonstrate the deoxygenation of oxygenates generated from the FTS process to improve the small olefinic fraction and the overall carbon yield to the valuable products.

The synthesis of high-efficiency and low-cost catalysts for hydrodeoxygenation (HDO) of waste lignin to advanced biofuels is crucial for enhancing current biorefinery processes. Inexpensive transition metals, including Fe, Ni, Cu, and Zn, were severally co-loaded with Ru on HY zeolite to form bimetallic and bifunctional catalysts. These catalysts were subsequently tested for HDO conversion of softwood lignin and several lignin model compounds. Results indicated that the inexpensive earth-abundant metals could modulate the hydrogenolysis activity of Ru and decrease the yield of low-molecular-weight gaseous products. Among these catalysts, Ru-Cu/HY showed the best HDO performance, affording the highest selectivity to hydrocarbon products. The improved catalytic performance of Ru-Cu/HY was probably a result of the following three factors: (1) high total and strong acid sites, (2) good dispersion of metal species and limited segregation, and (3) high adsorption capacity for polar fractions, including hydroxyl groups and ether bonds. Moreover, all bifunctional catalysts proved to be superior over the combination catalysts of Ru/Al2 O3 and HY zeolite.

Integrating mesoscale to the molecular level understanding of nanoparticle nucleation phenomena can drive the bottom-up synthesis approach for target applications. The authors studied the thermal evolution of binary metal oxide (cobalt and nickel oxides) nanoparticle structural phases on porous silica host from over wide spatial scale using multimodal analysis involving scanning transmission electron microscopy, x-ray absorption near-edge spectroscopy (XANES), and nuclear magnetic resonance (NMR) spectroscopy along with density functional theory (DFT) based calculations. The TEM analysis reveals thermally activated nanoparticle clustering and subsequent interaction with the porous host material. The Co and Ni K-edge XANES spectra revealed the evolution from metal hydroxide to metal oxide and subsequently metal silicate composites with calcination temperature. 29Si NMR analysis revealed the role of surface functional groups of silica host for silicate composite formation, which is corroborated by DFT studies.Integrating mesoscale to the molecular level understanding of nanoparticle nucleation phenomena can drive the bottom-up synthesis approach for target applications. The authors studied the thermal evolution of binary metal oxide (cobalt and nickel oxides) nanoparticle structural phases on porous silica host from over wide spatial scale using multimodal analysis involving scanning transmission electron microscopy, x-ray absorption near-edge spectroscopy (XANES), and nuclear magnetic resonance (NMR) spectroscopy along with density functional theory (DFT) based calculations. The TEM analysis reveals thermally activated nanoparticle clustering and subsequent interaction with the porous host material. The Co and Ni K-edge XANES spectra revealed the evolution from metal hydroxide to metal oxide and subsequently metal silicate composites with calcination temperature. 29Si NMR analysis revealed the role of surface functional groups of silica host for silicate composite formation, which is corroborated by DFT studies.

Alternative fuels derived from biomass “biofuels” are an attractive alternative to substitute limited and non-renewable sources of energy. Bio-oil generated from the pyrolysis of biomass is a complex micro-emulsion with high levels of oxygen and acids, which lead to increases in viscosity, phase separation, and degradation as it ages. This instability of bio-oil complicates storage, transportation and downstream processing. Currently, catalytic upgrading of is performed to stabilize the bio-oil by means of the reduction of the oxygen content. However, the current hydrothermal upgrading technologies operate at high hydrogen pressures, up to 2000 psi, and temperatures that lead to coke formation in the catalyst bed. A milder method is needed to convert unstable carbonyl species to more stable alcohols as an intermediate step before hydrothermal treatment. In this work an electrochemical approach has been investigated for the upgrading of bio-oil at low temperature using a proton exchange membrane (PEM) electrolyzer. The PEM electrolyzer was selected for performing the conversion as it avoids the need to add electrolyte to the oil which would cause phase separation and require later removal. Work has primarily focused on using cation-exchange membranes where protons are generated in the anode and travel through the membrane to the cathode surface. The hydrogenation of the bio-oil at the cathode competes with hydrogen evolution. Work has focused on using various electrode cell architectures and electro-catalysts to reduce both model compounds and actual pyrolysis oil derived from wood. While further work is needed, promising results have been observed with reduction of carbonyl groups and phenolic rings. A description of the work conducted and discussion of the results will be presented.